Manage your /etc from home-manager (install home-manager as root)

home-etc.nix

{ config, pkgs, lib, ... }: {
  imports = [
    (import <nixpkgs/nixos/modules/system/etc/etc.nix>)
  ];

  options.system.build.etc = lib.mkOption { type = lib.types.package; };
  options.system.activationScripts.etc =
    lib.mkOption { type = lib.types.unspecified; };

  config = {
    home.activation.setupEtc = config.lib.dag.entryAfter [ "writeBoundary" ] ''
      exec ${
        pkgs.writeScript "etc-activation"
        config.system.activationScripts.etc.text
      }
    '';
  };
}